Understanding Risk

Topics

Introduction

Colorado’s unique geography means that the state experiences a wide-variety of natural hazards. The state offers diverse landscapes including plains, mountains, mesas, and deserts, and with these many landscapes come a myriad of natural hazards and vulnerabilities. The 2013 Colorado Natural Hazards Mitigation Plan identifies 16 hazards that routinely threaten communities and cause damage, with droughts, wildfires, floods, and winter storms being the most impactful and widespread.

Natural Hazard Risks, as Perceived by Residents of Colorado

Drought occurs when precipitation is below average levels for a sustained period of time. Short droughts (under three months long) occur somewhere in Colorado nine out of every ten years. Multi-year droughts occur on a longer time cycle, and are impacted by the interaction of different components of the atmosphere-ocean climate system. Colorado has been affected by statewide multi-year severe droughts in the 1930s (Dust Bowl), 1950s and 2000s.

Flood

Colorado experiences dozens of floods annually; all counties and nearly all towns and cities (270 of 271) in Colorado contain flood-prone areas. Major flood disasters (warranting a federal disaster declaration) have occurred every five years on average since 1959. Floods are usually linked to severe weather and high rain; they may also be linked to seasonal conditions such as snowmelt, or catastrophic events like dam failure.

Tornado

Tornados occur predominantly on Colorado’s plains. Hundreds of tornados have been recorded in eastern Colorado over the past 50 years. While typically smaller than the tornados that occur in “Tornado Alley”, they can result in local damage to buildings and infrastructure.

Wildfires are pervasive across Colorado, with over 2,400 events per year. Fires may occur either in undeveloped areas (wildland fires) or at the interface between undeveloped areas and human settlement (wildland-urban interface fires). Many areas in Colorado experience regular ‘natural’ wildfires; fire is a part of the regeneration cycle of many forests and grasslands. However, humans cause numerous wildfires that would not otherwise occur, either voluntarily or by accident. Wildfire risks are exacerbated by long-term environmental stresses such as drought, low relative humidity, dry understory fuels and past suppression of fires, which results in an accumulation of combustible material.

Hail

Dozens of hail storms are reported each year in Colorado; since 1950. The state experiences an average of over 130 events per year, and hail has been recorded all parts of the state. Hailstorms frequently cause injuries, and in rare cases may cause death. However, the primary impact of hail is in property and crop damage.

Vulnerabilities

Every community faces vulnerabilities, be they natural or man-made. A community or individual can be considered vulnerable when they are exposed to a hazard (an event or long-term condition) and are likely to have negative impacts from this exposure. Communities that take action towards becoming more resilient reduce their vulnerability to adverse impacts from disasters and other events and can greatly improve their ability to bounce back afterward.

Shocks

Vulnerabilities are often described in terms of shocks and stresses. Shocks are direct vulnerabilities; they are intense, acute events that can disrupt communities. They include flash floods, wildfires, widespread loss of electrical power, dam failures, public health crises, and terrorist attacks. Shocks can lead to significant damage to infrastructure, as well as injuries and deaths. Communities use hazard mitigation as a means to reducing vulnerability by reducing exposure to shocks.

Activities Enhancing Our Understanding of Risk

Accurate, up-to-date information is critical for having a clear picture of the true risks a community faces. Missing or incomplete data can hamper the ability of public officials, emergency managers, the business community, and at-risk populations to make well-informed decisions for community and economic development. Communities can use this information to reduce their exposure to natural events that threaten public safety, health, and welfare.

A number of efforts are currently underway here in Colorado to enhance our understanding of the natural risks communities face. Read more about these efforts in the Plan Integration section of the Resource Center.

Stresses

In contrast to shocks, stresses are underlying long-term economic, social, and environmental conditions that can negatively impact a community’s environmental, social, and economic health; they are indirect vulnerabilities. Stresses can also limit a community’s ability to address and recover from a shock. Stresses can include aging infrastructure, an economic downturn, long-term high rates of unemployment, and a lack of affordable housing. Communities use resiliency planning as a way to reduce their indirect vulnerability by addressing and improving the underlying conditions that expose them to hazards and developing a capacity to adapt to changing conditions.

Stresses have the potential to intensify the impacts of shocks. For example, aging, weakened infrastructure may not be able to withstand a major flood event, which can impact emergency services, access to goods and jobs, etc. Multiple shocks can also lead to new stresses, for example, if multiple floods cause significant damage to a community’s commercial sector, it could lead to higher rates of unemployment.

Example of Interrelationship of Shocks and Stresses

Shocks and stresses are often interrelated. In this example, drought can exacerbate extreme conditions (dry vegetation, bare slopes) that leads to more damage should heavy rains fall.